Results of a multicenter study of the modified hook-titanium Greenfield filter

Evidence-Based Evaluation of Inferior Vena Cava Filter Complications Based on Filter Type

Many inferior vena cava (IVC) filter types, along with their specific risks and complications, are not recognized. The purpose of this study was to evaluate the various FDA-approved IVC filter types to determine device-specific risks, as a way to help identify patients who may benefit from ongoing follow-up versus prompt filter retrieval. An evidence-based electronic search (FDA Premarket Notification, MEDLINE, FDA MAUDE) was performed to identify all IVC filter types and device-specific complications from 1980 to 2014. Twenty-three IVC filter types (14 retrievable, 9 permanent) were identified. The devices were categorized as follows: conical (n = 14), conical with umbrella (n = 1), conical with cylindrical element (n = 2), biconical with cylindrical element (n = 2), helical (n = 1), spiral (n = 1), and complex (n = 1). Purely conical filters were associated with the highest reported risks of penetration (90-100%). Filters with cylindrical or umbrella elements were associated with the highest reported risk of IVC thrombosis (30-50%). Conical Bard filters were associated with the highest reported risks of fracture (40%). The various FDA-approved IVC filter types were evaluated for device-specific complications based on best current evidence. This information can be used to guide and optimize clinical management in patients with indwelling IVC filters.

Pharmacologic venous thromboembolism prophylaxis after traumatic brain injury: a critical literature review

Despite the frequency and morbidity of venous thromboembolism (VTE) development after traumatic brain injury (TBI), no national standard of care exists to guide TBI caregivers for the use of prophylactic anticoagulation. Fears of iatrogenic propagation of intracranial hemorrhage patterns have led to a dearth of research in this field, and it is only relatively recently that studies dedicated to this question have been performed. These have generally been limited to retrospective and/or observational studies in which patients are classified in a binary fashion as having the presence or absence of intracranial blood. This methodology does not account for the fact that smaller injury patterns stabilize more rapidly, and thus may be able to safely tolerate earlier initiation of prophylactic anticoagulation than larger injury patterns. This review seeks to critically assess the literature on this question by examining the existing evidence on the safety and efficacy of pharmacologic VTE prophylaxis in the setting of elective craniotomy (as this is the closest model available from which to extrapolate) and after TBI. In doing so, we critique studies that approach TBI as a homogenous or a heterogenous study population. Finally, we propose our own theoretical protocol which stratifies patients into low, moderate, and high risk for the likelihood of natural progression of their hemorrhage pattern, and which allows one to tailor a unique VTE prophylaxis regimen to each individual arm.

The mid-term efficacy and safety of a permanent nitinol IVC filter(TrapEase)

Objective

1) To evaluate the mid-term efficacy and safety of a permanent nitinol inferior vena cava (IVC) filter; 2) to evaluate filter effectiveness, filter stability and caval occlusion.

Materials and Methods

A prospective evaluation of the TrapEase IVC filter was performed on 42 patients (eight men, 34 women) ranging in age from 22 to 78 years (mean age 66 years). All patients were ill with a high risk of pulmonary embolism (PE). Indications for filter placement were: 1) deep vein thrombosis with recurrent thromboembolism; 2) and/or free-floating thrombus with contraindication to anticoagulation; and 3) complications in achieving adequate anticoagulation. Follow-up evaluations (mean: 15.4 months, range: 2 to 28 months) were performed at 6- and 12-month intervals after the procedure and included clinical histories, chart reviews, plain film, Doppler ultrasounds, and contrasted abdominal CT scans.

Results

In follow-up evaluations, the data analysis revealed no cases of symptomatic PE. There were no cases of filter migration, insertion site thrombosis, filter fracture, or vessel wall perforation. During the study, there was one case of filter thrombosis; early symptomatic thrombosis that was successfully treated in the hospital. Of the 42 subjects, eight died. These deaths were not related to the filter device or the implantation procedure, but to the underlying disease.

Conclusion

This study demonstrates that the TrapEase permanent IVC filter is a safe and an effective device with low complication rates and is best used in patients with thromboembolic disease with a high risk of PE.

An improved process for development and testing of vena caval filters: the percutaneous steel Greenfield filter

BACKGROUND

The purpose of this study was to develop a reduced profile stainless steel Greenfield filter with an over-the-wire delivery system and to compare its performance with the existing Food and Drug Administration-approved Greenfield filters. In addition, we wanted to standardize a system for evaluating filter prototypes.

METHODS

Percutaneous stainless steel filters with various hook configurations were evaluated for efficacy and safety in four in vitro modules designed to reproduce potential liabilities experimentally. Animal studies to assess thrombus capture and resolution, filter stability, migration, and hemodynamics were completed in 4 dogs and 38 sheep.

RESULTS

Mathematical modeling suggested that hook angle was the most relevant factor in improving resistance to migration. Prototypes that varied with respect to hook length and angle were evaluated in both the in vitro testing unit and in sheep. The stainless steel filter with two downward directed hooks provided clot capture comparable with the current Greenfield filter, maintenance of flow, and resistance to fatigue and corrosion while providing significant resistance to migration and penetration (p < 0.05).

CONCLUSIONS

The percutaneous stainless steel Greenfield filter with the alternating hook design provides a reduced profile device that can be placed over a wire to improve positioning. The use of a standardized testing system reduced both the time and cost of bringing this new device to the market.

Early and late results after Bird's Nest filter placement in the inferior vena cava: clinical and duplex ultrasound follow up

From February 1989 to November 1992, 61 Bird's Nest filters were placed in the infrarenal vena cava in 61 patients (36 men and 25 women; mean age +/- s.d., 63 +/- 15, range (16-83). In 27 (44.3%), the filter was inserted because of contraindication to anticoagulation, in 19 (31.1%) for anticoagulation failure and in 15 (24.6%) as prophylaxis against pulmonary embolism in high risk patients. All the filters were introduced by percutaneous puncture of the femoral vein after preliminary screening venography demonstrated that the iliac vein was free of thrombus. Two deaths occurred within 24 h of filter placement (periprocedure mortality 3.3%) while five other patients died within 1 month (30 day cumulative mortality 11.5%). At follow-up, 2-40 months later (mean +/- s.d., 17 +/- 9), a further 13 patients had died (cumulative mortality 32.8%). At 36 months, the probability of survival, calculated by the Kaplan-Meier Product Limit Method, was 55% (95% confidence intervals 37-74%). Apart from the two patients dying within 24 h, none of the early or late deaths were attributable to the procedure and there were no recurrent pulmonary emboli. Thirty-seven of the surviving 41 patients were recalled for clinical examination and Duplex ultrasound interrogation of the vena cava and the lower limb veins. No new venous thromboses in the legs were observed and no increase or onset of leg swelling was reported. The vena cava patency was 100% in these 37 patients.(ABSTRACT TRUNCATED AT 250 WORDS)